With the spread of personal computers (PC's), their performance is advancing at a great rate. As integrated circuit (IC) technologies advance, the volume of memory elements is constantly increasing along with performance characteristics of personal computers.
Computer users tend to purchase a computer at a price they can afford with a lowest acceptable memory mounted on the mother board which is expanded later as needs may be by plugging single in-line memory modules (SIMM's), dual in-line memory modules (DIMM's) or other memory elements into sockets provided for that purpose on the mother board. This arrangement makes it possible to buy a PC at a minimum investment and upgrade it later using up-to-date memory cards, thus providing an effective solution for both makers and users of personal computers.
Among connectors (or sockets) for such memory cards, SIMM sockets (e.g., U.S. Pat. Nos. 4,737,120; 4,850,892), DIMM sockets (e.g., U.S. Pat. No. 5,263,870), Small Outline DIMM sockets (e.g., U.S. Pat. No. 5,484,302), etc., are known in the art.
These sockets for memory cards comprise an insulative housing having an elongated slot with one or two rows of contacts arranged at a predetermined pitch along the slot. An edge of a memory card is inserted between the contact rows at one angle using low insertion force, after which it is rotated to a second angle resulting in the formation of spring loaded connections between contact pads formed along the edge of the memory card on one side (SIMM), or two sides (DIMM), and contacts of the socket. During rotation of the memory card to the second angle, the card is latched in the insulating housing of the socket by means of a latching device. When it is necessary, the latching devices can be released, the memory card can be rotated to the first angle and easily removed from the socket.
These memory cards may have either 150 contact pads (150P-type memory cards) or 144 contact pads (144P-type memory cards) arranged at a pitch of, for example, 0.8 mm on one or both sides of the card edge. These two types of memory cards are usually of the same thickness and the same height, but the length is either 70 mm or 67.6 mm. Because of the difference in length, memory cards of the 150P and 144P types can be used only in connectors designed specifically for that type of memory card. In other words, memory cards of the 150P type cannot be inserted in connectors for memory cards of the 144P type. Memory cards of the 144P type can be inserted in connectors for memory cards of the 150P type, but they cannot be retained in the connector housing by the latching device, resulting in unreliable electrical connections between the contact pads of the memory card and the contacts of the connector. Situations when it is impossible to use memory cards of the 144P type in connectors intended for memory cards of the 150P type, such as when the 144P card was purchased by mistake or was otherwise available, result in inconvenience for the user and additional expense.